diff options
Diffstat (limited to 'pkg/sentry/kernel/kernel.go')
| -rw-r--r-- | pkg/sentry/kernel/kernel.go | 176 |
1 files changed, 94 insertions, 82 deletions
diff --git a/pkg/sentry/kernel/kernel.go b/pkg/sentry/kernel/kernel.go index 0eb2bf7bd..9b2be44d4 100644 --- a/pkg/sentry/kernel/kernel.go +++ b/pkg/sentry/kernel/kernel.go @@ -430,9 +430,8 @@ func (k *Kernel) Init(args InitKernelArgs) error { // SaveTo saves the state of k to w. // // Preconditions: The kernel must be paused throughout the call to SaveTo. -func (k *Kernel) SaveTo(w wire.Writer) error { +func (k *Kernel) SaveTo(ctx context.Context, w wire.Writer) error { saveStart := time.Now() - ctx := k.SupervisorContext() // Do not allow other Kernel methods to affect it while it's being saved. k.extMu.Lock() @@ -446,38 +445,55 @@ func (k *Kernel) SaveTo(w wire.Writer) error { k.mf.StartEvictions() k.mf.WaitForEvictions() - // Flush write operations on open files so data reaches backing storage. - // This must come after MemoryFile eviction since eviction may cause file - // writes. - if err := k.tasks.flushWritesToFiles(ctx); err != nil { - return err - } + if VFS2Enabled { + // Discard unsavable mappings, such as those for host file descriptors. + if err := k.invalidateUnsavableMappings(ctx); err != nil { + return fmt.Errorf("failed to invalidate unsavable mappings: %v", err) + } - // Remove all epoll waiter objects from underlying wait queues. - // NOTE: for programs to resume execution in future snapshot scenarios, - // we will need to re-establish these waiter objects after saving. - k.tasks.unregisterEpollWaiters(ctx) + // Prepare filesystems for saving. This must be done after + // invalidateUnsavableMappings(), since dropping memory mappings may + // affect filesystem state (e.g. page cache reference counts). + if err := k.vfs.PrepareSave(ctx); err != nil { + return err + } + } else { + // Flush cached file writes to backing storage. This must come after + // MemoryFile eviction since eviction may cause file writes. + if err := k.flushWritesToFiles(ctx); err != nil { + return err + } - // Clear the dirent cache before saving because Dirents must be Loaded in a - // particular order (parents before children), and Loading dirents from a cache - // breaks that order. - if err := k.flushMountSourceRefs(ctx); err != nil { - return err - } + // Remove all epoll waiter objects from underlying wait queues. + // NOTE: for programs to resume execution in future snapshot scenarios, + // we will need to re-establish these waiter objects after saving. + k.tasks.unregisterEpollWaiters(ctx) - // Ensure that all inode and mount release operations have completed. - fs.AsyncBarrier() + // Clear the dirent cache before saving because Dirents must be Loaded in a + // particular order (parents before children), and Loading dirents from a cache + // breaks that order. + if err := k.flushMountSourceRefs(ctx); err != nil { + return err + } - // Once all fs work has completed (flushed references have all been released), - // reset mount mappings. This allows individual mounts to save how inodes map - // to filesystem resources. Without this, fs.Inodes cannot be restored. - fs.SaveInodeMappings() + // Ensure that all inode and mount release operations have completed. + fs.AsyncBarrier() - // Discard unsavable mappings, such as those for host file descriptors. - // This must be done after waiting for "asynchronous fs work", which - // includes async I/O that may touch application memory. - if err := k.invalidateUnsavableMappings(ctx); err != nil { - return fmt.Errorf("failed to invalidate unsavable mappings: %v", err) + // Once all fs work has completed (flushed references have all been released), + // reset mount mappings. This allows individual mounts to save how inodes map + // to filesystem resources. Without this, fs.Inodes cannot be restored. + fs.SaveInodeMappings() + + // Discard unsavable mappings, such as those for host file descriptors. + // This must be done after waiting for "asynchronous fs work", which + // includes async I/O that may touch application memory. + // + // TODO(gvisor.dev/issue/1624): This rationale is believed to be + // obsolete since AIO callbacks are now waited-for by Kernel.Pause(), + // but this order is conservatively retained for VFS1. + if err := k.invalidateUnsavableMappings(ctx); err != nil { + return fmt.Errorf("failed to invalidate unsavable mappings: %v", err) + } } // Save the CPUID FeatureSet before the rest of the kernel so we can @@ -486,14 +502,14 @@ func (k *Kernel) SaveTo(w wire.Writer) error { // // N.B. This will also be saved along with the full kernel save below. cpuidStart := time.Now() - if _, err := state.Save(k.SupervisorContext(), w, k.FeatureSet()); err != nil { + if _, err := state.Save(ctx, w, k.FeatureSet()); err != nil { return err } log.Infof("CPUID save took [%s].", time.Since(cpuidStart)) // Save the kernel state. kernelStart := time.Now() - stats, err := state.Save(k.SupervisorContext(), w, k) + stats, err := state.Save(ctx, w, k) if err != nil { return err } @@ -502,7 +518,7 @@ func (k *Kernel) SaveTo(w wire.Writer) error { // Save the memory file's state. memoryStart := time.Now() - if err := k.mf.SaveTo(k.SupervisorContext(), w); err != nil { + if err := k.mf.SaveTo(ctx, w); err != nil { return err } log.Infof("Memory save took [%s].", time.Since(memoryStart)) @@ -514,11 +530,9 @@ func (k *Kernel) SaveTo(w wire.Writer) error { // flushMountSourceRefs flushes the MountSources for all mounted filesystems // and open FDs. +// +// Preconditions: !VFS2Enabled. func (k *Kernel) flushMountSourceRefs(ctx context.Context) error { - if VFS2Enabled { - return nil // Not relevant. - } - // Flush all mount sources for currently mounted filesystems in each task. flushed := make(map[*fs.MountNamespace]struct{}) k.tasks.mu.RLock() @@ -561,13 +575,9 @@ func (ts *TaskSet) forEachFDPaused(ctx context.Context, f func(*fs.File, *vfs.Fi return err } -func (ts *TaskSet) flushWritesToFiles(ctx context.Context) error { - // TODO(gvisor.dev/issue/1663): Add save support for VFS2. - if VFS2Enabled { - return nil - } - - return ts.forEachFDPaused(ctx, func(file *fs.File, _ *vfs.FileDescription) error { +// Preconditions: !VFS2Enabled. +func (k *Kernel) flushWritesToFiles(ctx context.Context) error { + return k.tasks.forEachFDPaused(ctx, func(file *fs.File, _ *vfs.FileDescription) error { if flags := file.Flags(); !flags.Write { return nil } @@ -589,37 +599,8 @@ func (ts *TaskSet) flushWritesToFiles(ctx context.Context) error { }) } -// Preconditions: The kernel must be paused. -func (k *Kernel) invalidateUnsavableMappings(ctx context.Context) error { - invalidated := make(map[*mm.MemoryManager]struct{}) - k.tasks.mu.RLock() - defer k.tasks.mu.RUnlock() - for t := range k.tasks.Root.tids { - // We can skip locking Task.mu here since the kernel is paused. - if mm := t.tc.MemoryManager; mm != nil { - if _, ok := invalidated[mm]; !ok { - if err := mm.InvalidateUnsavable(ctx); err != nil { - return err - } - invalidated[mm] = struct{}{} - } - } - // I really wish we just had a sync.Map of all MMs... - if r, ok := t.runState.(*runSyscallAfterExecStop); ok { - if err := r.tc.MemoryManager.InvalidateUnsavable(ctx); err != nil { - return err - } - } - } - return nil -} - +// Preconditions: !VFS2Enabled. func (ts *TaskSet) unregisterEpollWaiters(ctx context.Context) { - // TODO(gvisor.dev/issue/1663): Add save support for VFS2. - if VFS2Enabled { - return - } - ts.mu.RLock() defer ts.mu.RUnlock() @@ -644,8 +625,33 @@ func (ts *TaskSet) unregisterEpollWaiters(ctx context.Context) { } } +// Preconditions: The kernel must be paused. +func (k *Kernel) invalidateUnsavableMappings(ctx context.Context) error { + invalidated := make(map[*mm.MemoryManager]struct{}) + k.tasks.mu.RLock() + defer k.tasks.mu.RUnlock() + for t := range k.tasks.Root.tids { + // We can skip locking Task.mu here since the kernel is paused. + if mm := t.tc.MemoryManager; mm != nil { + if _, ok := invalidated[mm]; !ok { + if err := mm.InvalidateUnsavable(ctx); err != nil { + return err + } + invalidated[mm] = struct{}{} + } + } + // I really wish we just had a sync.Map of all MMs... + if r, ok := t.runState.(*runSyscallAfterExecStop); ok { + if err := r.tc.MemoryManager.InvalidateUnsavable(ctx); err != nil { + return err + } + } + } + return nil +} + // LoadFrom returns a new Kernel loaded from args. -func (k *Kernel) LoadFrom(r wire.Reader, net inet.Stack, clocks sentrytime.Clocks) error { +func (k *Kernel) LoadFrom(ctx context.Context, r wire.Reader, net inet.Stack, clocks sentrytime.Clocks, vfsOpts *vfs.CompleteRestoreOptions) error { loadStart := time.Now() initAppCores := k.applicationCores @@ -656,7 +662,7 @@ func (k *Kernel) LoadFrom(r wire.Reader, net inet.Stack, clocks sentrytime.Clock // don't need to explicitly install it in the Kernel. cpuidStart := time.Now() var features cpuid.FeatureSet - if _, err := state.Load(k.SupervisorContext(), r, &features); err != nil { + if _, err := state.Load(ctx, r, &features); err != nil { return err } log.Infof("CPUID load took [%s].", time.Since(cpuidStart)) @@ -671,7 +677,7 @@ func (k *Kernel) LoadFrom(r wire.Reader, net inet.Stack, clocks sentrytime.Clock // Load the kernel state. kernelStart := time.Now() - stats, err := state.Load(k.SupervisorContext(), r, k) + stats, err := state.Load(ctx, r, k) if err != nil { return err } @@ -684,7 +690,7 @@ func (k *Kernel) LoadFrom(r wire.Reader, net inet.Stack, clocks sentrytime.Clock // Load the memory file's state. memoryStart := time.Now() - if err := k.mf.LoadFrom(k.SupervisorContext(), r); err != nil { + if err := k.mf.LoadFrom(ctx, r); err != nil { return err } log.Infof("Memory load took [%s].", time.Since(memoryStart)) @@ -696,11 +702,17 @@ func (k *Kernel) LoadFrom(r wire.Reader, net inet.Stack, clocks sentrytime.Clock net.Resume() } - // Ensure that all pending asynchronous work is complete: - // - namedpipe opening - // - inode file opening - if err := fs.AsyncErrorBarrier(); err != nil { - return err + if VFS2Enabled { + if err := k.vfs.CompleteRestore(ctx, vfsOpts); err != nil { + return err + } + } else { + // Ensure that all pending asynchronous work is complete: + // - namedpipe opening + // - inode file opening + if err := fs.AsyncErrorBarrier(); err != nil { + return err + } } tcpip.AsyncLoading.Wait() |